Considering a generator purchase - need advice

For your case, go with the two smaller ones. You'll get more power out of them and they are easier to handle. You can take only one if A/C isn't required. Not sure about Wen, but check out the Champion units of the same size as well.

Since you are only running them a couple times a year, make sure to get all of the fuel out of them and that the carbs are dry between uses so they don't gum up. Or at least use something like Stabil and run them once a month for half an hour.