Some bottles are just too useful or cool to recycle.
First, Halo 30ml cobalt blue with droppers, both handy and cool. You can buy appropriate tops to use them for nic freezing when breaking down a larger bottle. Same for most all 60ml glass bottles, which use the same cap. Thinking about it, I keep all the glass bottles lol.
Second, Mr E-Liquid triangular shaped bottles with thin needle tips. They are very pocketable polypropylene bottles and come in handy. Hands down the best 15ml and 30ml plastic bottles made, IMO.
Third, most plastic bottles with thin needle tips, just because those tips are very effective for refilling.
Lastly, in the realm of repurposing, 375ml Absolut bottles are handy for making 300ml batches and shaking them up!