I like:
75-125 HBCD
35-45g Peptopro or EAA
10g Creapure
8-10g citrulline malate (sometimes i take 4-6g pre and the remaining intra)
750mg to 1500mg Agmatine Sulfate is used when I have it.
I'm likely going to add TMG....2-4g
I don't really do the beta-alanine thing simply because it would be optimal to consume 1g 4x daily or 1.6-2g 2x a day and I just don't get around to keeping that kind of schedule with it and it takes weeks to really notice. There is a new analog of it that will probably be available in the next year or two where you can take far more at once...and there are no tingles and it doesn't take as long to build.
I had high hopes for Hydromax Glycerol but it looks like the product Glanbia was putting out did not meet specs and I have talked to a couple people that claimed they didn't notice much or anything from it.
Taurine is a good one and cheap as well and possibly glutamine when using slin or if you need it for stomach health.
The drink I use now (No Slin) is a lot like Knight9's who I drew direction from along with Meadows and Mike Arnold's protocol drink. It's just a slightly streamlined version, less carbs, no BA. Few tweaks. I will probably try some Intra-MD as a base once my other ingredients run out. I have noticed fuller pump when using this as well as better recovery (especially when dieting and normally eating LESS carbs).
50-75g HBCD (GlycoFuse, Orange Mango), 15g PeptoPro natural vanilla, 10g Creatine, 6g CM, 1g Agmatine, 2g Taurine, 8g of BCAA (bulk USPlabs "bulk" Modern 8:1:1 ratio (NP carries it), will be switched to EAA when it’s out), 8oz of Powerade (orange or tropical, added electrolytes, carbs, flavor), remainder is water up to about 1000ml. Taste is 10/10 but not too sweet or sugary. I drink about half of it 15min prior so its "in the blood" and the remainder sipped throughout.
On Slin (which I havent done yet), I would Bump the HBCD to 100g, bump Pepto to 25g, add 10g L-glutamine (extra insurance), bump BCAA to 10g and add more water, 1200-1400ml total.
Obviously you can make these things better and better buy just adding more but I try to keep it streamlined with cost as a consideration. I have PRO/CHO 2hrs before workout and immediately after too so I dont see that spending tons extra on 40-50+ grams of Pepto and 15+g EAA/BCAA in each shake makes a huge difference. Obviously a lot more CM/Agmatine is always better but I try to use just enough to make it worth it without ending up with a $10 shake every day.