If you are a beginner I don't think big power like a 270 or 290 is going to be a problem. You should just put on a slow throttle that will keep you out of trouble. When I started as a beginner my first bike was a BETA rev 270, It was a great bike for me to start with. All bike brands are fine, Montesa and Beta are probably the most durable, where as Gas Gas are light and have a nice clutch. If finances are a factor I would by the bike in the best condition and not worry about brand. A 200 cc or larger will be fine. Good luck
Steve Singer