Bike Mirror (drop handlebars) Recommendations, Please.

I used to have a CatEye BM-45, but I found it too small to get a good view. Switched to a Zefal Dooback 2, I can see a lot more with that. On the downside it is, as the kids say, fugly.

IZefal spy mirror on 2 bikes and works well for me. Have mine mounted at the end of the drop with the mirror on the inside of the drop. I do occasionally knock it with my knee but easy to re-adjust on the move. I have tried on the outside of the bar but find that my forearms obstruct the view when riding with my hands on the shifters. 
 

https://www.zefal.com/en/mirrors/110-spy.html

I have the B&M Cycle Star 60mm (photo below), which is a tad bigger than the 45mm Cateye. I set the position once and leave it there, it doesn't need tweaking mid-ride.

It is very sturdy, metal & plastic construction, with a glass convex lens.

It is also available in a larger 80mm diameter.

I bastardized a Mirrycle MTB mirror to make mirrors for my fleet of bikes with drop bars. The arrangement has stood the test of time and been in use for ~25 years. Essentially the mirror is just a Mirrycle mirror with the handlebar plug cut off. The important bit is the 2.5mm aluminium attaching it to the brake hood. Up and down movement on the arm is minimised by the depth of the arm, and I have reduced sideways movement by putting a slight roll in the flat metal along the arm.

The wing nuts on the mirror enable it to be easily adjusted if necessary while on the road, as well as allowing the mirror to be folded out of the way when the bike is up-ended to fix a puncture, etc

Over the years, I've progressively modified this design slightly to improve on it. Below is the latest permutation. 

It no longer looks quite like the original arrangement. The lug at the rear is now only used to stop the rear cable tie from slipping off, and it doesn't slip under the brake hood as the original model did. Apart from that, the arm itself is the same as before. The use of cable ties enables the mirror to be held more firmly onto the brake lever housing, thus further increasing its stability. The locking ends of the cable ties are strategically placed on the inboard part of the brake lever housing in a position that doesn't foul one's fingers. I've found this arrangement to be quite comfortable on the hands, so no further padding, etc is required, nor does anything foul the brifters in any way.

I have the Bike-Eye mirror which fits on the frame on the down tube up at the steerer. I set it so the view just skims the seat and seat tube.

I've used them for about 10 years now.

The pros are that you get a stable image and you can see cars readily. This basic pro far outweighs the following list of niggles.

The cons are you need to learn the habit of using them, you look between your legs and depending on how you cycle you sort of time your view to fit with a lifted leg though these days I am not conscious of doing anything - perhaps my thin thighs are thinner than they were. Occasionally I knock the mirror if I'm scooting around - easily adjusted. Final negative is that the old design was based on traditional tubing and the mega down tubes of modern bikes don't match the fitting so well, but it works well enough (I think I used my own extra long zip ties and nots of insulating tape to protect the frame to fit them on my Giants). FInal point is that in a group, the mirror being relatively low means that you can't see around people behind, though I solve that by moving further out if I want a gander.

I've tried bar end mirrors but they are a bit more fiddly and prone to being knocked when parked.

I wouldn't ride a bike without one - I did that last year on an old mountain bike and I thought it was a scary experience. In the club I got the reputation for being the guy who actually was aware what was going on behind.

I've tried a couple of different ones:

Italian Road Bike Mirror: https://www.italianroadbikemirror.com/ItalianRoadBikeMirrorWorldwide.html

Sprintech: https://www.sjscycles.co.uk/accessories/sprintech-racing-road-mirrors-black/

They both had a similar issue of not being easy to adjust to be in the perfect position and not retaining their position. The Italian RBM is held in place by handlebar tape, which is awkward for making adjustments - maybe someone more skiled than me would get them to work well.

I've been using the CatEye BM-45 for a few years and it's great as it holds its position well and can be adjusted whilst riding (choose a clear bit of road though). It can be tricky getting it just right for switching between tops and drops, but it works well for me.

I think the cateye is ok. HP and Sriracha were using it which lead me to try it.

You do have to set it up carefully and if on the tops I find I have to raise my elbow to see, but fine otherwise.

I've been thinking recently that the utility of a mirror probably outweighs its uncool factor. Very tempted by one of these:

https://www.spacycles.co.uk/m2b0s192p3918/GILLES-BERTHOUD-Bar-End-Mirror 

I've only recently converted to using a bar end mirror.  Unhelpfully, I'm just going to say I'm very happy with the CatEye.