This is going to be subjective some people are die hard Align folks. But to answer your question I have a small list of great 450 helis (ones that swing 325mm blades)
In no particular order:
1) MS Heli Protos Mini
2) Gaui X3
3) Compass Warp 360
4) Align 450L
As for what electrics to use, stay away from all Align electrics there are better options available.
For motors not to many choices Sorpion is the only name that pops into my head for a 3S setup
For a 6S setup (with 350mm and up blades) you can add KDE Direct into your list. Servos I would
consider RJX or there knock off brand. For your ESC you have Scorpion, Kontronic and Castle. Gyros
are going to be your big issue, which one do I go with. I would look at the new Spartan
Vortex along with the standard ones (i.e. iKon, B.D., Skookum, BeastX, V-Bar etc, ect, ect). Blades I really
like the Rails blades at 326mm but the choice is yours on those.
When looking at cost you need to factor in your crash cost. Start looking at what alike parts cost across the brands. I found Gaui to be the most cost effective overall. Its a solid kit, designed well and now with the X3 having a belt option for the tail you cant go wrong. One other gimmik that Gaui has done is added some plug ins for your esc and servos right into the frame. I think its still being developed but TSH has released images of there idea. I am really liking it except for it being on G10. I own 2 of those kits mentioned. I can say that spending the money on a really good kit is always going to be better in the long run. The issue is how much do you spend on the kit, as much as you can afford. While Monstro is a quality kit I would not recommend it unless you willing to spend the cash. That one heli will suck you dry the first time you crash.