I have many options readily available to choose from, but if I were to choose just one, - if I had to go with one round for the rest of my life (444 or otherwise) it would be the NOE/RD432-300 bullet (295gr when cast with WW) over 45gr of H4198. Velocity is about 2250fps from a 22" barrel and accuracy is consistently sub-moa.
The 290gr LFN from Beartooth Bullets actually weighs the same as above mentioned bullet and reportedly favors the same 45gr of H4198. Beartooth bullets have a waiting list that commonly runs about 6 months. For commercial bullets, the 290gr bullet from Beartooth may be the best "do-it-all" bullet in the 444.
Carolina Bullets has the Ranch Dog 432-265 bullets available. Those are great bullets in the 444.
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If you are buying just one powder, RL7 has proven to be a great performer with all bullet weights (187gr-417gr)
Both the Beartooth Bullets and Carolina bullets offer their bullets sized .432" which is commonly the optimal size for cast bullets in our 444 Marlins.