Stal:
You have a TS, so the considerations for a BS aren't much different: table size, power, blades, maneuverability, cost, and mass are some of the ones I can think of.
Bigger, heavier, more powerful machines typically operate more smoothly, with less vibration. That's great unless you have to move it into place to use it and/or store it, or just have a smaller shop. Purchase price is of course an issue. The old adage does hold: You get what you pay for. I have purchased all of my equipment used from individuals who have advertised here on NCWW or on Craigslist. So all of that is general advice for WW machinery.
Specific to a BS - I would not really consider a bench top BS, and or any of the three wheeler machines. They have the illusion of being able to do what you need, but tracking the blade, and any other adjustments are generally painful and transient (i.e it is hard to keep these guys operating the way you want a BS to operate). I would suggest trying to find at least a 12" (the wheel size) or 14" (much more common size) machine from any the typical WW brands (Jet, Rikon, Delta, etc). Of course to fit your budget that may need to be a used machine. I have just read on other wood related bulletin boards that capable WWers have purchased new 10" benchtop BS (I believe both Jet and Rikon) and eventually returned them because they could not get or keep the blade to track properly. This is of course second hand, now third-hand 'knowledge' or more appropriately opinion.
Finally, if cutting curves is what you want to do - then many times a good jigsaw with a good blade (i.e. a Bosch or DeWalt etc, not a $15 B&D or Craftman) can accomplish that quite well. A zero clearance plate helps with the quality of cut here.
In my view a BS is a better choice for:
- cuts in thick wood (>2"; though some jigsaws can handle that well too)
- resawing boards to thinner pieces,
- roughing bowl blanks to round for the lathe
- ironically - it is often safer for cuts in small pieces
A good jigsaw is a great choice for really big pieces that would be tough to tackle with a BS, pieces up to 2" thick, and cutting many curves.
I hope that helps - posting more info about the types of projects you do, and would like to do, would help others make more specific recommendations.
Henry