Jay_D

I also highly recommend Ride With GPS. Per your requirements:

1. See on the same screen the map with my Strava route highlighted — Import/Export in RWGPS is pretty good with multiple formats. I run RWGPS, and use it's navigation, and SYNC completed rides to Strava.
2. (I don't need turn by turn though) — The FREE version doesn't have voice-enabled turn-by-turn. As mentioned, the $6 per month Basic subscription gives pretty good voice instruction. Regarding cost, RWGPS lets you suspend your subscription, so I only use it during the months I ride.
3. and a few customizable data fields (speed, HR, cadence, elevation, time...). — All you list plus the basics are there, including the ability to link to sensors. I currently link to the Bontrager DuoTrap S speed and cadence sensors.
4. And when needed swipe to see more data fields or a full screen map — you can do this, but I find it tough while riding to remember all the swipe sequences. UI could be better, but seeing the full map is ideal and I use it often.
5. free or cheap subscription — As mentioned, there are 2 paid subscriptions. The lower cost Basic subscription gives voice instruction and the ability to plan routes, and the higher price subscription is for those doing more extensive route planning. Regarding cost, RWGPS lets you suspend your subscription, so you can subscribe during the months you ride, and suspend it otherwise.
6. Import GPX files — RWGPX has a list of 5-7 import/export formats, including GPX.

Implied or Assumed or Not Mentioned & Consideration Needed

• Use of Strava — I use RWGPS as my primary navigation and tracking solution, and syncronize completed rides to Strava. RWGPS has a number of "Connected Services" that will send ride information to other solutions. I currently SYNC to Strava and Apple Health. I am investigating a new bike computer for visible, real-time speed & other stats,
• Multi-platform mobile: Mobile app is available for both Apple iOS and Android. Members of my team are on both Apple and Adroid phones with no issues.
• Web interface or portal — there are some things that are just better than the phone. In particular, the calendar, stats, import/export functions. But for RWGPS, route planning on a large monitor is great. I don't care for Strava's web interface although I no longer subscribe to Strava.
• Mounting your phone securely — To me, this is critical. All the other posts about visibility are true. Combine those with not wanting to drop the phone, and this is a priority item for me. I use and highly recommend the QuadLock system. I have mounts on 2 bikes, and keep the case on my phone. It has a "rain coat" if needed. I've used this system for years and I'm on my second phone using it, and the only changes have been the case (iPhone 6s was a different size than the iPhone XS), and I changed from the Stem Mount to the Out Front mounts.

Downside

• I like seeing speed, cadence, (someday HR), duration, and distance while riding. You cannot keep your phone display on. It needs to be bike friendly.
  • I use a standard bike computer, and I'm looking to upgrade soon if I find something that integrates with both the DuoTrap S and my Bontrager ANT+ light system
• Long ride battery time, especially as your phone ages.
  • I have a top tube bag for long rides and carry a power bank. The bag stays zipped and the wire plugs into the phone to recharge.

My Configuration:

• iPhone XS running RWGPS & Strava
• Display goes off after [1 min ±] inactivity
• Bontrager DuoTrap S sensor, with speed and cadence sensors
• Bontrager Ion 200 & Flare RT lights (plus the Pro RT when needed)
• Bontrager Trip 300 bike computer (looking to replace & upgrade this
• BlueTooth speaker in bike shirt pocket — voice instructions shared with the crowd.
• Mounts on primary bike:
  • Bontrager Blendr has the front Ion 200 light plus the Trip 300 computer
  • QuadLock Out Front mount facing backward, positioning phone mount over the stem
• Mounts on my old bike:
  • QuadLock Out Front Pro mount positioning phone mount out in front the stem. There is a mount slot below the phone mount for a GoPro or something else that I'm currently not using.
  • I use a Cateye Strada computer there, speed sensor only, mounted on the handlebars. It does not sync with RWGPS.

I have a library of Routes with voice instruction, Points-Of-Interest, from 10–110 miles that came in handy when training from my house during COVID. I belong to a club that uses it for their ride library. I participating in 1 major and a couple of minor events per year and they all use it. The integrations with Garmin, & Wahoo are attractive to me, but others are using Hammerhead & Lezyne computers/sensors also. From my initial use, the mapping/routing are far superior to Strava, and both RWGPS and Strava support import/export. I find RWGPS to be the best solution for using your phone as a bike computer and highly recommend it.