While I can't remember if the box art was a motivating factor in the purchase of any kits as a kid, I do recall being in awe of the Airfix B-17G "A Bit o' Lace" artwork and probably spent more time staring at the boxtop than building the kit! I also remember thinking the Airfix box art for their PBY-5A, Arado AR-196, Fairey Firefly, Halifax, Stirling, Marauder and Grumman J2F Duck were pretty cool too. Strangely, it was only a few years ago that I eventually bought myself an Airfix J2F, and although the later box art is actualy quite boring, I'm sure it was the memory of those early days spent drooling over the Airfix catalogues that inspired the purchase (but of course, in true adherence to Murphy's Law of modelling No. 1, the kit was surpassed by the release from Pavla not long after my purchase!). I also only recently bought my first Airfix Stirling, Halifax & Marauder. These purchases were spurred by the announcement of Airfix's demise, so I thought I'd grab them while they were available. Of course, Murphy's Law struck again with the B-26!!!
I also recall being attracted to the Frog JU-88 box art as a kid (though I never bought one) and their Macchi Folgore and Spitfire Mk.VIII box art were pretty cool too, I thought.
Although not wonderful, I always felt that the box art of the Matchbox Hawker Fury and A.W. Siskin captured their lines very nicely and it probably contributed to my purchase of these kits. I also liked their Buckeye box art too and only recently bought my first one of these from Ebay. The T-2 isn't an aircraft that I'd normally be attracted to, so I suppose the box art won in this case.
I checked my Excel listing of past and unbuilt kits (all 1:72) and have come up with the following list of kits where the box art either dictated or contributed to the purchase. There are undoubtedly others but this list includes aircraft that are not really within my usual field of interest, so I have to admit that the box art won me over: LS Pitts Special, Smer Spitfire Vc (big disappointment inside the box), Roden Albatross W-4, A-Model Kamov KA-62, Italeri F-100, MPM Albacore, Roden Felixstowe F.2A, Sword Fairchild 91, Hasegawa Ki-61, Dragon He-162, A-Model KOR-1, Pavla Ro.57, Revell Hunter F.6 & Frog Blackburn Shark.
Other kits that almost made this list due to their attractive box art but that I have managed to refrain from buying are: Revell Fiat G-90, Gavia Turbolet, Hasegawa CT-133 "Black Knights" and an Academy ship kit that really grabbed my attention (it was either the Cutty Sark or the USS Eagle, but I can't recall now; I just remember caressing the box on several trips to the LHS but eventually deciding against it).
Cheers all!