hey Danny,
I have two epip LP's and one gibson LP all from the 1990's. in my opinion gibsons were made better in the 90's then they are right now or since then. Also there's plenty of Gibson LP's that are quality, but don't carry a hugh price tag. a les paul studio for example was roughly 700 bucks brand new back then, and is probably somewhat in the same price range. really the only major difference between these and a $2000 standard is the studio has no binding. this made them big sellers for gibson in the 90's.
there's also the studio lite, which is the same guitar, but is had a thinner body by about quarter of an inch, was hollowed out inside but instead had uber lite air plate hobby wood inserted inside instead of a cambered body. the result is a les paul that is lighter then any strat you can find, but still had an amazing LP thump. right around 2000 (give or take a year) gibson re-released the exact same guitar in the version of the les paul gothic. the only difference was it had a satin black finish, and all black hardware. also you probably could get for under 1000.
the LP specials were great in the 1990's as well, and I love the P-100 pickups in those (stacked p-90's) also in the late 90's was the LP studio GEM series, which was a studio with the old school p-90 pickups and the guitar came in awesome colors like ruby and amethyst for example.
the higher end models are going to be the standards, classics, and customs. the classic was gibson take on the 1960's LP at that time, and were amazing looking and playing guitars. By the 2000's gibson starting putting in these overly yellowed pearl inlays in the necks and they looked so fake to me. if you come across a classic plus or classic premium plus, it's just a classic with a more flamey maple top and heavier price tag.
also 1999 gibson reissued the LP deluxe as a 30th anniversary, and I think the LP deluxe (the originals or the reissue) ranks up there in the top ten greatest guitars ever put out by gibson.
on the epiphone side, the LP customs and standards are pretty well made. they have a poly finish, and in the 90's the epips had a alder back, mahagony neck, and maple top. they sound great, but may lack the typical LP thump just a little because of the alder. still great sounding guitars. however, the pickups on these were typical not wax potted, or just had squeeling problems in general (microphonic feedback), at least all the ones I played. of course I used a lot of high gain too, but even on a somewhat clean tone I struggled with them. back then the LP customs ran about 700 and the standards ran about 500, and again without checking ebay prices my guess they are priced roughly the same today.
the 2000's epip's switched to a mahogany back at some point, and I think the humbuckers were improved by then, a lot of the epips were made in the US too, so I think the quality got a little better. the customs and standards a little pricier, but I stopped paying attention to epip spec as much by that time, since I had begun my love affair with the mosrite
I probably would avoid anything lower then a epip LP standard because you'll get more into beginner quality guitars at that point.
If you do go with a 1990's epip LP, i dont think it will disappoint, but you may want to change out the pickups and the cheaper pots at some point down the line with higher quality parts. on one of my epip LP's I have a seymour duncan JB and Jazz humbuckers in them and that's a great combination, in the other guitar I switched to all standard gibson stock parts, gibson 490 and 498 humbuckers, which has been a staple humbucker for gibson for decades.
hope some of this info helps
!