It depends on the pad stack and pad reach you want to ride:

• In both the 2018 and 2019 frames, there is a choice of stem (65mm or 85mm) that changes the pad reach range possible.
• In the 2018 frames there is choice of 3 base bars and because of where the pads / spacers mount that changes the pad stack ranges possible on each.
• In the 2019 frames, the arm rests mount to a central pedestal, but the pad stack range is smaller and with a like for like "flat" 2018 base bar also a bit taller.
• As noted above there is a team switch plate kit that allows the 2018 arm pads to be both narrower and less pad reach. There is also an angled spacer kit both of which are ordered when you configure the bike.
• The 2018 bikes have a 1-piece bottle, the 2019 bikes is 2 piece that joins under / through the arm pad pedestal.

In my case for pad stack = 620, pad reach (centre) = 509, bb-saddle = 809 (albeit I raced this season at a pad reach (centre) of 533. I'm 181cm tall, but long limbs):

• 2018 medium, 85mm stem, flat bar and pedestalled up quite high. With the longer pad reach I rode this year, it would be the absolute max pad reach possible.
• 2018 large, 65mm stem, drop or the flat bar with relatively few spacers. On the flat bar I cant go down much (~15mm max), the drop bar I'm very near the middle of window, but would need the team switch plate for less pad reach. (Actual pad reach without the switch plate when set like this should be 511).
• 2019 large does not fit as too much pad stack. 2019 medium would fit with the 85mm stem and pedestalled like the 2018 bike.

Anyway I actually ordered a 2018 large, 65mm stem, drop bar and the various accessories. The one-piece bottle and a front-centre much closer to what I like / am used to riding swung it for me. The other bike that would sensibly work for me is a Trek SC, but all depends on your fit.