Migrating

sp command	sf command
disaggregate	st_cast
plot(x)	plot(st_geometry(x))
coordinates(x)	st_coordinates(x)
coordinates(x)=~x+y	st_as_sf(x, coords = c("x","y"))
over(x,y,returnList=TRUE)	st_intersects(x,y)
over(x,y)	sapply(st_intersects(x,y), function(z) if (length(z)==0) NA_integer_ else z[1])
spDists(x,y)	st_distance(x,y)
aggregate(x,by,mean,areaWeighted = TRUE)	st_interpolate_aw(x,by,mean)
merge(x,y)	merge(x,y)
CRS(projargs)	st_crs(proj4string)
proj4string(x)	st_crs(x)
proj4string(x) <- p4s	st_crs(x) <- p4s or st_set_crs(x, p4s)
spTransform(x, CRSobj)	st_transform(x, crs)
bbox(x)	st_bbox(x) or matrix(st_bbox(x), 2) to get the same output as bbox
x@data	st_set_geometry(x, NULL) or st_drop_geometry(x)

Full list of commands, exported by sp:

sp command	sf command
addAttrToGeom	st_sf
areaSpatialGrid	*
as.character.DMS
as.double.DMS
as.image.SpatialGridDataFrame	*
as.numeric.DMS
as.SpatialLines.SLDF	st_geometry
as.SpatialPolygons.GridTopology	see st_make_grid
as.SpatialPolygons.PolygonsList	-
bbexpand
bbox	st_bbox
bpy.colors	sf.colors
bubble	see plot, use pararameter cex
cbind.Spatial	cbind
char2dms
compassRose
coordinates	for POINT: do.call(rbind, st_geometry(x))
coordinates<-	see arg coords in st_as_sf, or st_set_geometry
coordinatevalues	*
coordnames	* (in sf, coordinates are unnamed)
coordnames<-	-
CRS	st_crs
dd2dms
degAxis	(integrated)
degreeLabelsEW	(integrated)
degreeLabelsNS	(integrated)
dimensions	see class(x) with x an sfg, geometry object; this is not similar to st_dimensions!
disaggregate	see st_cast
flipHorizontal
flipVertical
fullgrid	*
fullgrid<-	*
geometry	st_geometry
geometry<-	st_geometry<-
get_col_regions	-
getGridIndex	*
getGridTopology	*
getLinesIDSlot	-
getLinesLinesSlot	-
get_ll_TOL
get_ll_warn
getPolygonAreaSlot	-
getPolygonCoordsSlot	-
getPolygonHoleSlot	-
getPolygonLabptSlot	-
getPolygonsIDSlot	-
getPolygonsLabptSlot	-
getPolygonsplotOrderSlot	-
getPolygonsPolygonsSlot	-
get_Polypath	-
get_PolypathRule	-
get_ReplCRS_warn
gridat
gridded	*
gridded<-	*
gridIndex2nb	*
gridlines	*
gridparameters	*
GridTopology	*
HexPoints2SpatialPolygons
identicalCRS	== method for crs objects
IDvaluesGridTopology	*
IDvaluesSpatialPixels	*
image2Grid	*
imageScale	*
is.projected(x)	!st_is_longlat(x)
layout.north.arrow
layout.scale.bar
Line	see st_line
LineLength	see st_length
Lines	-
LinesLength	see st_length
longlat.scales
makegrid	*
mapasp
mapLegendGrob
merge	merge
over	see st_intersects
%over%	see st_intersects
panel.ggmap	-
panel.gridplot	-
panel.pointsplot	-
panel.polygonsplot	-
panel.RgoogleMaps	-
plot	plot
point.in.polygon
points2grid	*
Polygon	see st_polygon, st_multipolygon
polygons	st_geometry
polygons<-	st_set_geometry
Polygons	-
print.DMS
proj4string	st_crs
proj4string<-	st_set_crs
rbind.SpatialLines	rbind
rbind.SpatialLinesDataFrame	rbind
rbind.SpatialMultiPoints	rbind
rbind.SpatialMultiPointsDataFrame	rbind
rbind.SpatialPixels	rbind
rbind.SpatialPixelsDataFrame	rbind
rbind.SpatialPoints	rbind
rbind.SpatialPointsDataFrame	rbind
rbind.SpatialPolygons	rbind
rbind.SpatialPolygonsDataFrame	rbind
read.asciigrid	see st_read
recenter
remove.duplicates	see st_union on multipoint
select.spatial
set_ll_TOL
set_ll_warn
set_Polypath
set_PolypathRule
set_ReplCRS_warn
Spatial
SpatialGrid	*
SpatialGridDataFrame	*
SpatialLines	see st_sfc
SpatialLinesDataFrame	see st_sf
SpatialLinesLengths	see st_length
SpatialMultiPoints	see st_sfc
SpatialMultiPointsDataFrame	see st_sf
SpatialPixels	*
SpatialPixelsDataFrame	*
SpatialPoints	see st_sfc
SpatialPointsDataFrame	see st_sf
SpatialPolygons	see st_sfc
SpatialPolygonsDataFrame	see st_sf
SpatialPolygonsRescale	see st_sf
spChFIDs	-
spChFIDs<-	-
spDists	st_distance
spDistsN1	see st_distance
sp.grid	-
sp.lines	-
split	split?
spmap.to.lev	-
sppanel	-
sp.panel.layout	-
spplot	plot, ggplot
spplot.key	-
spplot.locator	-
sp.points	-
sp.polygons	-
spsample	st_sample, st_line_sample (partial support)
sp.text	-
sp.theme	-
spTransform	st_transform
summary	summary
surfaceArea	-
write.asciigrid	see st_write
zerodist
zerodist2

* concerns gridded/raster data, not supported by sf

- irrelevant

relevant commands, exported by rgeos

rgeos command	sf command
gArea	st_area
gBinarySTRtreeQuery
gBoundary	st_boundary
gBuffer	st_buffer
gCentroid	st_centroid
gContains	st_contains
gContainsProperly	st_contains_properly
gConvexHull	st_convex_hull
gCoveredBy	st_covered_by
gCovers	st_covers
gCrosses	st_crosses
gDelaunayTriangulation	st_triangulate
gDifference	st_difference
gDisjoint	st_disjoint
gDistance	st_distance
gEnvelope
gEquals	st_equals
gEqualsExact	st_equals_exact
getScale	st_precision, st_set_precision
gInterpolate	see st_line_sample
gIntersection	st_intersection
gIntersects	st_intersects
gIsEmpty	st_is_empty
gIsRing
gIsSimple	st_is_simple
gIsValid	st_is_valid
gLength	st_length
gLineMerge	st_line_merge
gNearestPoints	st_nearest_points
gNode	st_node
gOverlaps	st_overlaps
gPointOnSurface
gPolygonize	st_polygonize
gProject
gRelate	st_relate
gSimplify	st_simplify
gSymdifference	st_sym_difference
gTouches	st_touches
gUnarySTRtreeQuery
gUnaryUnion	aggregate
gUnion	st_union
gWithin	st_within
gWithinDistance	st_within
readWKT	st_as_sf
setScale	st_precision, st_set_precision
version_GEOS	sf::sf_extSoftVersion()["GEOS"]
version_GEOS0
writeWKT	st_as_text

relevant (non-raster) commands, exported by rgdal

rgdal command	sf command
checkCRSArgs	st_crs
CRSargs	st_crs
get_OVERRIDE_PROJ_DATUM_WITH_TOWGS84
getPROJ4libPath
getPROJ4VersionInfo
llgridlines	st_graticule
make_EPSG
ogrDrivers	st_drivers
ogrFIDs
ogrInfo	print
ogrListLayers	st_layers
OGRSpatialRef	st_crs
project	st_transform
projInfo	st_proj_info
projNAD
rawTransform
readOGR	st_read, read_sf
RGB2PCT
setCPLConfigOption	see argument options of st_read
set_OVERRIDE_PROJ_DATUM_WITH_TOWGS84
showEPSG	st_crs
showP4
showWKT	st_as_text(crs)
writeOGR	st_write, write_sf