Which would you rather? LP550-2's can be had for a good price and they're plenty fast. I feel like the only downside with the 550 is it doesn't have a dual clutch, but maybe that makes it more visceral? The 458 is phenomoal but much more of a physics-defying machine than a raw supercar. The V10 is nice too. Obviously having both would be ideal. Also, you can find 6-speed manual LP550 coupes, but you cannot find any gated spyders! That car would be a good investment! Part of me thinks an LP550 Spyder E-gear would be a good investment also, but they'll probably make a RWD Huracan. Always been a diehard Porsche-Ferrari guy. Lately I've been appreciating something about Lambos and that is something seen specifically in the Gen II Gallardos: the reserved styling and image that seems to be a lot cooler than the 458. 458 is beautiful, but very wide and flamboyant. Lambo and a 911 -- very cool. 458 kind of gaudy. 430 Scuderia, and 458 Speciale however -- not gaudy at all.
You cannot go wrong with either the 458 for 550. It boils down to which one you like best. Finding a manual LP-Gallardo spyder is very difficult and they are not cheap. If you're selling the car in the next 2-5 years, both are going to depreciate, if you're going to hold onto to it longer, the ferrari will likely level off and being to appreciate more quickly. There is a 2WD Huracan, it's the 580 car.