Only 2 fixed-base 15A routers I know of are the Porter-Cable 7518
and the Milwaukee 5625
Both are tried-and true workhorses, as much power as you'll be able to get in any router. Neither are going to offer you above-the-table bit changes with a single wrench. The P-C has enough room in the base casting for a grapefruit, the Milwaukee looks like it might not pass your 3-1/8 panel bit but they offer a "Production Base Assembly"
that might fit your requirement.
That's about it for fixed-base heavy-duty production routers, not a lot to choose from.
If this is your lift Jessem Rout-R-Lift
it looks like the adapter ring has enough holes to fit almost any router.
Lots of plungers that'd do all you want, ultimate in build quality and reliability would have to be the Festool OF 2200
. Pricey little sucker, though. You'd probably want to take your ring to a Festool dealer just to make sure it's got holes to fit or call Jessem to verify. But if you only want to buy one more table router the rest of your life this would be my suggestion.
For other 15A plungers, check out DeWalt 625, Bosch 1619, Makita 2301, Triton 001(seems to be a favorite around this forum), P-C 7539. All have their pros and cons, you can find infinite # of discussions and reviews on each. My big plunger is B&D/Elu 3339, predecessor of the DW 625. Dates back to early '90's, parts still available. Wouldn't allow 3-1/8 bit, DeWalt has changed base so maybe 625 would. Bosch advertises 3-3/4 base opening, rest don't say.
Spend some time on this forum searching, Google, go to dealers and kick tires. You'll find something that'll suit you.