As mentioned previously, there is no right or wrong (except for front-mount jacks and Teles; see the earlier comments), but here are a few suggestions, hopefully in alphabetical order by guitar manufacturer:
Brian May (see Burns); Burns London Brian May, Steer, Marquee, Scorpion, Double Six, Bison (basses and six-strings) — DEFINITELY angle plugs (it's easy to whack a straight plug and crack the pickguard); Ibanez (RG370DXGP, JEM7V, RE2EX1, RG4EXQM1, RG3EXQM1, JS1200, RG1470) — we like angles; ESP (LTD Deluxe EC-1000, F-50) — we'll shove an angle plug in there and be happy with our choice; Fender Jazz and P-bass — a Death Valley guitar cable with an angle (but straight is fine also); Dean (VX, Vendetta XM, Evo XM, EVO Noir, Z-X Electric, MLX, ML Noir XT, Baby ML, Dimebag Razorback, Explosion Razorback, Dime-O-Flame — an angle plug on a Death Valley Cable Company guitar cable; Gibson Les Paul (and clones) — we like angles (especially the G & H angle plugs on one of our handmade guitar cables).
Les Paul Junior — also angle; Melody Maker — angle; Gibson emi-hollow bodies ( Casino, Wildkat, Sheraton, ES-175, ES-335, ES-137, Korina Explorer, Dot Archtop, Dot Studio — angles, especially when the jack is in the body front (you can crack the body if something whacks into one of those straight plugs sticking out of the body, and we have seen it happen).
Gibson SG — an angle danglin' on the end of a DVCC guitar cable; Gretsch (G5120 Electromatic Hollowbody, G5135 Electromatic Corvette, Pro Jet, Electromatic hollowbody, Junior Jet, G5265 Jet Baritone, G6131SMY Malcom Young I Signature) — angle plugs; Jackson (JS30RR Rhoads, RR3 Rhoads, DK2M Dinky, WRXT X Warrior, KE3 Kelly, DK2 Dinky, Custom 24, CE 24 Maple Top, Custom 22 10 Top, xtSA with Synth Access, LGXT) — snap in an angle plug; Line 6 Variax — angle; Mackie mixers — straight plug on a DVCC guitar cable.
PRS (SE Single Cut, SE Custom) — angle; — Strat-type guitars — usually straight but angle will work; Schecter (C-1 Hellraiser, Damien -FR, Omen 6, C-1 Classic, Gyphon Limited Edition Flametop, C-1 Artist Limited Edition, Vengeance Standard, M-200FM, LTD Viper-100FM, LTD FX-260 Spalted Maple, EC-50, KH-202 Kirk Hammett Signature Model) — we like angle plugs (on DVCC guitar cables of course), but straights work just fine; Steinberger (all models) — an angle plug and a Steinberger go together like, well, pancakes and syrup.
Telecaster-type guitars — DEFINITELY straight (plug won't seat in some deep jacks); Washburn (A20 Flamed Top, HH Ash, HH, Lipstick, Stardust Retro-H 12-string, NJC Bich, STR-1 Pro Electric Sitar) — we like angles; Yamaha — all angle plugs (terminating a 20-foot length of CBI guitar cable).