Go with your heart. Just be sure, if you end up going the cello route, to strive towards getting as big and deep a tone out of the cello as you would out of the bass. One of my favorite cellists is David Soyer and a big part of that is because of the depth of tone he was able to get out of the instrument. Granted, I wasn't fortunate enough to have heard him live, but I get fooled (sometimes) into thinking he's playing double bass about every time I watch this clip
Full disclosure: part of (or all of?) my post (and I apologize if I've derailed this thread before it even got started) may have had me ranting a little due to my experience playing in orchestras where the cello "section" was comprised of whiny soloists each doing their own thing instead of a full, big toned, for the common good section sharing certain parts with the bass section (i.e. providing the fundamental support for the rest of the orchestra/melody).