I have been using the YSI Pro 1020 that I picked up used from a friend and like it quite a bit. It takes about 15-20 minutes to "warm-up" and stabilize before you can get consistent readings, but once it's ready...it's fast and easy. It reads DO, Temp, and PH. My cord is only about 4 foot long though. I don't think you can go wrong with the YSI brand.
I have been using the "API POND MASTER TEST KIT 500-Test"
for the last 2 years and have been happy with it. It's about 25$ from Amazon and tests pH, Ammonia, Nitrite, and Phosphate. It is the test tube and dropper type which is not as handy as the electronic devices, but money talks. I took a 2x4 and drilled blind holes in it to hold the test tubes for adding the drops. That makes it much easier and quicker to perform the tests. I can test all the parameters in 10-15 minutes. This kit will last many years even if you are doing water tests every week. Maybe not in Florida due to the much longer pond season, but certainly a couple years.
The downsides compared to the expensive electric devices are...
1.) It's resolution is a bit wide, meaning you really can't tell what the readings are to a precise point. ie - PH can be determined to be between 6 and 6.5, but you'll be hard pressed to know that it is exactly 6.3. NOT a big deal for pond water. I have cross checked it with my electric DO/PH meter and it is always very close.
2.) The lighting available for comparing the test tubes to the chart can make it mildly questionable. Fluorescent bulbs will give a different reading compared to daylight, incandescent, etc. Still, not a big deal...just the difference between a little above a ph of 6 or a little below. I always use the same light in my shop to stay consistent.
2.) Easy to use.
3.) It utilizes the proper ranges for ponds.
I have also used the "CHEMetrics K-7512 Dissolved Oxygen Kit, 1-12 ppm Range"
and like it too, but it is a bit expensive to use frequently. But, it works well and much like the API test tube kit. I have since purchased a hand held DO/PH meter and cross checked the Chemetrics to find them very close as well.
There is a thread I started on my pond for water chemistry and you all might find the whole thread interesting, but the very first post is where I have collected and saved ALOT of info pertaining to pond water chemistry that I, mostly, found here on PB. If nothing else the first post is worth digging through. Here it is...https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=508843