There are of course opinions all over the place on this topic.
It's up to you of course to decide how much you want to spend, and the look you want. That's what it really all boils down to.
For my part, I have over 10,000 miles on the ME880's with the recommended oversized front and rear tire sizes (see my pix in the signature link below). There were no fitment issues. There have been no "expansion" or other interference issues after the install. The mechs that put them on did not come to me and say something like, "they won't fit" or "we have to modify or move (fill in the blank here
) to get your rear tire past the swingarm." There are/were no rub marks on either side, or the top, of either tire.
The bike definitely handles more securely with the larger sizes. They look better on the bike, too.
Despite all the hubub you may be hearing or reading elsewhere, the recommended larger sizes just fit
Depending on how it's done and who does it, you may in fact have to let some air out of the rear tire on install to get it to clear, but of course it's no big deal to fill it back up afterwards.
The Metzelers may in fact cost a bit more than some of the others, but I now have over 10k on both, and their treads look great. I'd say the back is good for another 10k; the front, at least several thousand more, anyway. For a while, these were the factory tires on the Yamaha Raider. Not sure if they still are, or not.
I've also ridden these tires some in the rain. They have not let me down.
To help keep flat tires and blowouts at bay, be sure to use/install "Ride On" tire sealant in your new "shoes" after you put a few hundred miles on them. Someday, you'll be glad you did.
Check the date of manufacture on your new tires (preferably b4 they're installed!). They shouldn't be more than several months old, if that.
It helps airing up a lot
.....if you order and install a diagonal
tire valve stem in the rear tire. Go with the all metal version only.
Hope some of this helps.....