From a user's perspective the lifetime upgrades are obviously better options as you get more advertising and you pay once only. I'd rather go that way..
When I first took lifetime upgrades, I thought like that. The problem is so many new site owners get in over their head then close down.
I don't expect the site be around my lifetime but at least provide a few years of benefit. I guess owner reputation is the best attribute to
determine site longevity.