Best shoes for me on the market are the new Giro line of shoes. They offer different levels of performance that include Easton carbon soles. They fit 'like a glove' and are arguably the most comfortable lightest, and stiffest shoes I ever owned.
When I began road cycling, I used to wear a pair of mtn bike shoes, and when I made the transition to a road shoe, it was almost night and day. Now I have a pair of Giro Factors and all I can say is 'wow'. I recommend whatever shoe you go with, definitely make sure that the sole is stiff and the shoe is light. Make sure that there is no flex at the toe too.
The best cycling shoe is one that fits your feet. Yes, that is kind of a given, but you would be amazed at how often people buy shoes because of some advertising message or price and the shoe doesn't fit. Anyway, on road bike shoes you want a very stiff sole (different from mtn bike shoes where you want flex for walking). Amount of mesh, velcro straps or ratchet, etc are personal preference. Weight won't differ much from one to another, the biggest benefit over mtn bike shoes is stiffness, allowing greater force to the pedals). Finally it is important to have a shoe that will mount your preferred cleat/pedal system. Go to a local bike shop or two and try them on. Price will vary widely; you can also order online (see second sentence) from places like Nashbar, Performance, Colorado Cyclist, etc as long as you can return them if they don't fit.
I'm guessing you are useing mtn. shoes because you have a big foot. First pair of road shoes .......hhhhmmmmm Shimano. They have a big toe box, and depending on your wallet. You can go cheap (less than 100 bucks), or go for all the whisles and bells. They won't stear you wrong. Keep the tires on the pavement, good luck.
I have to agree that Specialized Body Geometry (Pro Road in particular) are my favorites. I happen to have a great barely used pair of 46A's available for sale. See the listing here: https://post.craigslist.org/manage/2586944708
Your post does mention a good shoe that is not too expensive. SIDI makes perhaps the best quality shoes, but they do come at a price...The best value out there currently is the GIRO Factor...It is reasonably priced, and packs features that even more expensive shoes do not offer...The 2 biggest features that benefit performance, are 1)a good quality stiff carbon sole, and 2) a fastening system that forms the shoe to your foot for maximum fit and comfort...The GIRO Factor does both...It has a stiff and light Easton EC90 carbon sole, and a ratcheting strap for on the fly adjustability...The tongue is also slit to form to the top of your foot, and the insole has different arch inserts to match your foot...These shoes are extremely light as well...as a comparison, I own a pair of the best road shoe SIDI has to offer, the Ergo 2....I LOVE this shoe...but I also LOVE my GIRO Factors, and they are 60 grams per shoe lighter than the SIDI's!...That's 120 grams of rotating weight...That is significant, considering how many revolutions per minute you have to move those shoes over the course of a ride....There are many good shoes out there, but when you're looking at product value, the GIRO Factor is it...They're about $269...(The SIDI Ergo 2s are $500)...Good luck!
Go to a bike shop and try some shoes on. Everyone's feet are different. Certain brands will not fit your feet as good as others because of the size and width of your foot. This one bike shop only carried in stock Louis Garneau shoes and he told me that they didn't fit my feet real good and even though he'd like to sell me a pair of shoes, what he had didn't fit my feet good. So he sent me to another bike shop and they had some Scott shoes and they fit my feet really good, so that's what I bought. They were about $90, so not too expensive.