New AC in Austin, TX

My house (built in 1996, 2800 sq ft) has two HVAC systems both installed in an unconditioned attic, one serving upstairs (1500 sq ft), one serving downstairs (1300 sq ft). The upstairs condenser and evaporator is original to the house and the evaporator has developed a leak in the primary drain pan. It still cools well, but relying on the secondary drain pan isn't a good long term solution. It uses R-22 so just replacing the coil isn't a great idea. The compressor is 3 tons. The furnace was replaced less than two years ago with a Carrier gas furnace with a PSC blower. It is a -070 (70kBTU.)

I have talked to three local reputable companies who have all provided me with similar options. All equipment quoted was Carrier.

1. New condenser & coil, ~14 SEER, base model. 24ABC636 condenser, CNPHP coil

2. Complete new system, furnace, condenser, & coil. ~16 SEER, single stage compressor. ECM/variable speed blower. 24ABC636 condenser, CHPNP coil, 58CVA090 furnace. It appears that the added efficiency is purely from the furnace, but it is a bunch more money to throw away a fairly new furnace.

3. Complete new system, furnace, condenser, & coil. ~17 SEER, two stage compressor. ECM/variable speed blower. 24ACB736 condenser, CHPNP coil, 58CVA090 furnace. The only difference from the previous option is the compressor.

4. Variable speed compressor, infinity system. Not really considering this option given the cost and no one has convinced me it provides substantially better benefit that option 3.

Different companies quoted different size coils seemingly randomly. Varied between a 36, 42, and 48 capacity. If I understand correctly a larger coil will be (slightly) more efficient at cooling and a smaller coil will be (slightly) better at dehumidification.

One weird thing is that all the quotes were replacing the furnace with a -090 when I know I don't need more heating capacity.

I keep my house pretty warm (80 deg) in the summer and the AC has no problem keeping up, but I am from a dry climate and cannot stand humidity. It is really bad in the spring and fall when the cooling load are low. This last month has been between 70 and 90 degrees outside with between 70 and 95% RH. Indoor I have been keeping the house at 74-78 deg and the indoor humidity has been between 60 and 70 %.

On the single stage AC, I can get a 2.5 ton, which is probably a more reasonable size, but the 2 stage only comes in whole ton increments, and 2 tons probably isn't enough.

So now the question. What option should I go with, and should I consider another option (such as a whole house dehumidifier (I know what teddy bear will say)). A whole house dehumidifier plus option 1 probably costs the same (or even less) than option 3.

Thanks for your input, hopefully that wasn't too much text to read.