My suggestion would be to measure your thighs and your waist (either at your hips or just above your hip bones) and then choose the proper size of harness. If you are between or near the edge of the size range I would opt for the smaller size. All of these brands make high quality products. If you can afford it try to buy one with more padding and you will be more comfortable in the long run.
I just got back into trad climbing after a 15 year layoff, now i am chubby, feel old and have worn out joints but i still i climb 1-2x weekly as i love it, i really force myself concentrate on technique as i cant rely on muscling my way through a route.
i did realize dropping a little weight will help my game and make me a more solid climber so i have been working on it. My goal is to drop about 20lbs