You didn't say what type of amp you have and what its power ratings are, but ...

The major variables that will determine which speakers can be driven, regardless of stand-mount or floor:

Speaker Sensitivity - The more sensitive, the easier to drive. To drive a speaker with a 86dB sensitivity rating to a loudness of given level will take twice the power as one rated at 89dB to go to the same volume level. So speaker sensitivity, not really whether it is a stand-mount or floor speaker, will  largely be the factor.
Speaker Impedance - The lower the impedance, the more current is demanded from the output section of the amp. 4 Ohm speakers are harder for an amp to drive than 8 Ohm speakers, in general. Check the amp power ratings for its capability in driving lower impedance speakers before purchasing speakers with a lower impedance.
Room size - Things being equal, a larger room will require more acoustic output from the speakers/amp than a small room. Also, a smaller room may be more appropriate for stand-mounters than a larger one. I have stand-mounters in my 11x14 den but floor models in my 30x16 living room.
Desired listening Level - The louder you like to listen, the more acoustic output will be required from the speakers/amp.
Amp Power - The above factors will determine whether a given amp can satisfy the requirements for driving the speakers with given sensitivity and impedance, in a given room, to the desired volume.

These factors combine to determine whether a given amp/speaker combination will work well in a given situation, not really whether the speakers are stand-mount or floor.

Given that, you are probably aware that there are trade-offs to stand-mount and floor speakers. A generalization is that floor models tend to have better/deeper bass and stand-mounts better imaging/sound-staging. Therefore, the type of music you like may help determine the speaker type you would be most happy with.

Reply with the amp you have, room size, type of listening you do, type of music you listen to, and some of the speakers you have in mind and others or myself may be able to give you more specific advice.

Jerry
Cranky Audio Guy, Inc.