I currently have a rubicon unlimited, with 35's , flat flares, performance leveling kit. Looking to go up I think, just not sure on 2.5" or 3". I do have bumper and winch and will soon be adding rear bumper and spare. Would it be better to get the 3" and just let it settle or the 2.5" and add spacers as needed? Any suggestions would be greatly appreciated.

 

I'm sure that many others will chime in. To me, personally I'd go with either. Either one should give you the clearance you need to allow for your tires and the weight of aftermarket accessories, bumpers and such.
There will probaly be alot of opinions here regarding drivetrain changes, to me both a 3" and a 2.5" would have minimal if any major changes but research your lifts, there are some 3" kits out there that people are getting 4" with and that could put you higher than you want to be. So to me researching your lifts is going to be important. Good luck in your choice.

 

I'm leaning towards rock krawler or terra flex will there be any drive line issues going up to the 3" lift?

 

I don't know about rock krawler but i looked at Tera Flex when I was shopping for my kit. I had read that people were getting 5+" out of the 4" kit and people getting more than 3" out of the 3' kit. The teraflex rep is on the forum here as well as rockkrawler, look them up and ask away on the questions. It is a big move and you want to be sure you leave no questions unanswered before you purchase.
Reach out to forum members and ask for pics of each lift/ tire size combo your interested in. ask forum member who are running the lifts you are interested in to give you feedback on their experiences

 

Get one that you can upgrade in the future. You may decide later on you want to get more lift.