Oh, as far as what kind? I also learned on a drop in bobbin machine. I think that, maybe, if you can find a really nice OLD singer (by old I mean early seventies or sooner) at a repair shop with a repair person who can do "support" and show you how to use it, how to adjust the settings, etc, they tend to be very reliable and functional machines, and you may get years of use out of it (I had my first one for eight years, and my mom had it for 20 years before that, I think, maybe fifteen) before you're ready for a new one. The only reason I got a new one was that i was moving out, and my sister claimed my old machine (mom had "given it to me to USE" not keep)...and I got one almost exactly like it, and used it for another 9, before my husband brought me a NEW machine...frankly, I still use the old singer easily as much as I use the new one (though the new one is a well built machine...).
all that to say, find something inexpensive, till you decide what you want/need/like in a machine...but know that you can get inexpensive AND high quality (much higher, actually, than what you'd get for the same price at places like sears/target, etc) in a well built old machine.

have fun!