I'm not aware of any basic central AC system sold in the US today that does not use a Copeland scroll. Even value brands like Goodman use them instead of Bristol recips like back in the day when I helped on the first CAC rulemaking (anno 1999). Only VS compressors like the panasonic in the Nordyne, or the rotaries found in some mini-splits / RAC's / PTACs are not scrolls.
If budget is a concern, there are plenty of gas storage water heaters that allow direct vent. Simple, keep the combustion gases outside, etc. Easy to replace too. Powered units should allow more freedom re: venting materials (see Vertex, for example) but may be noisy.
As for the furnace & AC unit, I think the installer is a bigger factor than the brand, all things considered. If you're in a cold part of the country or use propane, condensing furnaces are usually a no-brainer. Staging may help comfort and/or zoning. Similarly, a 16 SEER AC system may be a good deal after rebates, state, local, utility incentives. I'd look into both.
One thing to always check also is whether your system is compliant re: the static pressure drop requirements set out by the manufacturer. I.e. are there sufficient supply / return ducts of the right size, etc. to ensure the thing can do its job. It's always amazing for me to see a six-figure job done wrong!