If you have neck issues and may need the bars higher, get a size 54 bike, but in a relaxed geometry frame. The Allez you mentioned in the OP is a race frame meant to be ridden aggressively.
Originally Posted by
DaveSSS
A 54cm Synapse would be a good choice. The 165mm head tube would allow you to get a very small saddle to bar drop of only around 3cm, with a common 84 (-6) degree stem and about 2cm of spacer.
I agree with Dave. A 54 Synapse has more relaxed geometry but is still closer to the correct size for you. If your flexibility increases over time, you can always make the Synapse a little more aggressive while still remaining comfortable to you. If you went with an Allez, you could make it slightly more relaxed but you'd be fighting the frames' purpose at that point.