My favorite Bi-Plane is my sig.
No doubt that the Nieuport 28 is a pretty cool plane. It got a bit of a bum rap with the first American squadrons that flew it due to some wing fabric failures. This problem was later fixed, but the N-28s were replaced by Spad 13s anyway.
I think that in some ways, the N-28 was a better plane than the Spad 13. Eddie Rickenbacker stated that it was more maneuverable; a fact that stood him in good stead when he was attacked by an Allied Spad 13 once.
Here are some photos of the Smithsonian’s Nieuport 28 that I took a few years ago:

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I’d like to see a new 1/72 scale kit of the Nieuport 28.
Regards,
U-2VS: the nightwitch sewing machine of death and destruction. [:D]
The Grumman F3F series, the flying barrel, for me. I’ve built 2 of the 1/48 AM kits.
Regards, Rick
I really Like the Albatross DV and Sopwith Pup but the Stearman is way up there too.
Boeing PT-17 Stearman and Fokker D-VII. I have built models of the Fokker, but not the Boeing.
Darwin, O.F. [alien]
I like the Henschel Hs-123, The Boeing P-12E, Curtiss P-6E and the Curtiss BF2C and Hawk 2 (used as a fighter/bomber by the Chinese) as well as the Curtiss SBC3/4 which has used during WW2 fro patrol use.[:)]
albatros DV

Several planes come to mind, such as the Curtiss Hawk II, Fokker D VII, He 51 A and B versions, Type 93 intermediate trainer and I know that they are not Bi-planes but I have to add them to the list the Hansa Brandenberg W29, Fokker VIII and the Fokker E III.
Cheers,
Eric
Gotta go with the Swordfish first.
Close seconds: DH-2, Boeing F4B-4, Tiger Moth.
I like the Curtiss F9C-2 Sparrowhawk. Just saw one today… neat little bird!
Historically, has to be the Swordfish. Smacked the bejesus out of the Bismarck, & would’ve given Prinz Eugen & Scharnhorst a decent touch-up too. Close 2nd:- Gloster Gladiator. worked it’s whatsy off in all the Med campaigns, & earned it’s stripes admirably.
No I don’t have a Sword - yet. Yes I do have a Glad - picked up the Roden Mk1 today. Can’t wait to get started. Quite like the look of the Hs 123 too - might have to add that one to the build shelf soon.
Henchel Hs 123, Gloster Gladiator (In all those lovely export marking), DH Tiger moth and Dragon Rapide, Handley Page HP 400, Avia B-534, Fairey Albacore and without doubt the Antonov An-2.
FIAT CR 42
I’m building Italeri’s new kit, as per my sig.
Karl
Also vote for the Gladiator and Swordfish. Also like the Walrus, Seagull, CR 32 and 42. Always liked pretty much any that flew in WWII.
WWI would have to go with the Dr 1, Dr VII, Neuport 28 and Camel.
Beechcraft D-17S “Staggerwing”. Why oh why is there no good kit of this significant (not to mention beautiful) airplane. And, I don’t want no sissified G-17; gotta be a D-17, P&W engine, preferably in consular markings.
Just my opinion, of course.
Phil
I have always liked the Avia B-534 myself, although I like any biplane. Other favorites include the An-2, SPAD XIII, and the old WACO and Eaglerock planes too. Also any of the older transports and mailplanes… The M-2 is one I am going to build a flying model of someday.
Curtis P6E Hawk, Beautiful Bird.
Again, the Gladiator and Swordfish get my vote,brave or lunatics, those guys went up against superior aircraft and got the job done.
You gotta love the Pitts Special, though.