Best route from Anaheim, CA to San Diego?

Thanks! We stayed at Desert Wils on our way to Anaheim and found it to be a good choice. Very convenient to all services.

SD to Bullhead. 15/215/40 is what the mapping app provides. However, there is probably still a lot of construction on 215, especially near San Bernardino. And it is still pretty hairy around UC Riverside. Tiny bit longer, but I'd recommend taking 15 to the 40. 95 up to Bullhead.
Be advised that commuter traffic will be heavy in the morning heading out of SD. Especially problematic is around Temecula. Were I making that drive, I'd leave around 10am from SD and spend the night at Desert Willow RV, just off the freeway in Hesperia, just over Cajon Pass. It's not a destination park by any means, but has full hook-ups with a lot of shopping, etc., nearby. We like to walk across the street to Five Guys for a burger.

We did the reverse, SD to Anaheim about a month ago. It is the easiest of the routes available and should be taken. The 91/215 route, depending on the time of day, is a heavy commuter corridor. But that applies to all SoCal driving.
I will add, that if you came into Anaheim from the north via 5 and you hit the mess we hit when we left Anaheim for Pismo, all that construction, at least as a month ago, was to the north of Anaheim.

Taking I-5S or 405S is not a bad drive. Obviously 405 and 5 join together in El Toro. Right along the beach with lots of beautiful scenery. If you're lucky, you can watch the tanks perform at Camp Pendleton. Excellent small towns such as La Jolla as you near San Diego. (Hint: You'll most likely want to avoid Blacks Beach).

Easiest way out is I-15 N to 40E to 95N.....Dennis

From Anaheim-- 405 S to the 5 S or just get on the 5 depending where you are in Anaheim--to San Diego--about 2 hour drive depending on traffic. From San Diego to Bullhead City-- 15 N to the 40 E to AZ-than 95 to Bullhead City. Lars

From Anaheim you really don't have much choice, your 1/3 there. Either the 5 or the 405. Coming back you can take the 215 North to the 15 and hopefully miss most of the traffic and road construction, (but it has traffic too).
Just plan on a long slow drive, it the traffic is light you can be pleasantly surprised.

You can always take the 91 east to I-15 south,in Corona then to the I-215 into San Diego. A bit farther but it isn't the I-5.

Just reverse your route back up the 215 to I-15 to I-40 east to Needles then up 95 to Laughlin and Bull Head.