If you're asking what fleet boxes, on their own, make for playable stuff, I'll recommend the Drakh, Dilgar, EA boxes, Brakiri, and ISA.
The Dilgar gives you what you really need -- scouts, decent Skirmish ships (you WILL later on want to add Omelos to your fleet) and the most important part, the Targrath, in quantity (4). The carrier is pretty much useless, but there it is. The Tikrit is useful, and the Mishakur --- well, if you just imagine it's a similar-looking Mankhat, you're great. Expansions you'll want later: several Omelos, more Targraths, one Tikrit, maybe a Rohric or two (last is very optional). Can support up to 6 Battle and small change.
The Drakh almost give you the same, quality ships at every priority level. 3 Scouts, more than enough Raiders, 3 Light and Heavy Cruisers give you scouting and firepower at every level. You also don't get stuck with any of those gosh-awful Fast Destroyers, thank God. You get a Mothership, too, which is a reward and a problem --- that Mothership is why it's almost impossible to find this boxset anymore. Expansions you'll want later: an unbelievable quantity of Raiders, a second Mothership (good luck finding that!), at least 3 more Light Cruisers. Can support up to 7 Battle and small change.
The Brakiri is the one league race, that, if you field it by itself, is workable. While it only has 3 ship classes, it gives you the best of what they have -- Ikortas that you'll call Brikortas, 4 Aviokis that you'll call Kalivas, and 2 Tashkhats you'll likely call Takatas. No patrol options does hurt, though. Expansions you'll want: rest of the league (expensive), at minimum several small Vree scouts. A Brokados will be selected, too. Can support up to 9 Battle.
EA Early years really gives you a fleet to work with, but its maximum point theshold isn't that high, getting you only 5 Battle. But all the ships are capable and coherent, and you'll be covered in virtually every low priority-level fight with gobs of options. Expansions you'll want: one Avenger carrier, many more Saggitarius, several Hyperions. Can support up to 5 Battle.
The last capable box is the ISA, with tons of WS's that could be WS-2's if you need them to be. Too bad you get two Victories -- you'll only ever need 1 -- I think. You'll also run into the very first ISA player problem --- where are my Skirmish ships? Some players are still lookin'. Expansions you'll want: White Star Carrier, Vree Scouts (again), a few of the Nolo'tar Skirmish thing no matter how good or bad it is. Can support up 9 War, so bring it, baby.
The complaints for the beginner's ears about the other fleet boxes:
1). The soul of the game is the Raid ship, and the Minbari one only gives 2 of them at that priority or below.
2). The Centauri are stuck fielding Vorchans from their fleet box. Ew.
3). And the Narn don't get any members of the Bat Squad, just T'Loths and G'Quans.
4). The Vorlon gets two Heavy Cruisers, one of which you will not ever use.
5). the Shadows have a bazillion Armageddon-level Shadow Ships, which is at least half a bazillion too many
6). Abbai miss a couple of classes, but, as a fleet, on their own, they haven't struck wonder without masses of Tiracas.
7). Drazi as a race are very hard to fly by themselves; otherwise, fleet box is very good.
8). Vree as a race to themselves are extremely hard to win with, Xorr just doesn't get the job done.
9). You will probably never use all 3 P'Shul'Shi Convoy Guardians at once; and where are all my Sunhawks and Warbirds? You mean I gotta buy a Drazi box, too?