Tbh these options depend on the bracket, and since this is in 19s i don't really know why faps & saps are in the poll, but that's beside the point. Speed potting and rocket boots in 19's is the most bracket-ruining. Premading into pugs is a close second, but other than that for 19s nothing comes close. There are only a few speed boosts in 19s, such as
https://classic.wowhead.com/spell=2983/sprint (50%),
https://classic.wowhead.com/spell=16618/spirit-of-the-wind#used-by-npc (30%) from blood shard quest, and of course
https://classic.wowhead.com/item=7189/goblin-rocket-boots (70%) and
https://classic.wowhead.com/item=2459/swiftness-potion (50%). Rocket Boots and Speed Pots are *bad* for the bracket because there aren't many ways to keep up with them. In fact, there is no way to compete with rocket boots unless you have them equipped yourself. Because of that, you are using an almost unnecessary speed-boost just to.. idk what you would do, cap a flag? Anyway, Rocket boots and speed pots is my first choice for those reasons. But, you can do whatever you want because its your own character and nobody can really tell you what not to do if it's not against Blizzard's Rules.
Premading vs pugs is my second option. If you are ever 5-man (OR MORE) queuing into pugs, you are hurting the game, and here's why: Because you are coordinated (or at least I hope you are if you're 5-man queuing), you will stomp the pick-up group on the enemy team. Because of your amazing prowess on the battlefield, some of the levelers on the opposing faction will probably stop queueing and just level. Then, because the levelers aren't queuing as much BECAUSE of your 5-man, queues will inevitably start to slow for all parties involved. Nobody wants to wait 20 minutes to get into a bg anyway. Because you are premading versus pugs, (either for reputation or just for "fun") you'll end up hurting yourself and friends because of your actions. (and if you say you aren't stomping pugs with a 5-man queuing, you're either lying, or your group is less-than-desirable at the objective.)
Anyways idk why i took so long to write this but those were my options and my reasonings. (P.S. In higher brackets i.e. 39+, I wouldn't say rocket boots and speed pots are as bad because of the many other speed boosts available in those brackets. In the 39 bracket, they're replaced with Sappers and faps.)